Graphic artists working in a digital medium generally have a choice to use a tablet or a pen display for creating drawings. Generally, a tablet will have to be connected to a display. With a tablet, the artist puts a stylus pen to the tablet surface, but the drawing appears on the separate display not the tablet. With a pen display, the artist puts the stylus pen to the display surface, and the artist is able to view the drawing on the same surface as it is being created with the stylus pen. Both tablets and pen displays have a digitizer that converts a physical input from the stylus pen into electronic signals which are then translated into images corresponding to the physical input. The most common type of input device for a digitizer of tablets and pen displays is a stylus pen.
A stylus pen is basically a writing instrument but made to work with electronic devices to create digital images. There are various technologies that can transfer the contact pressure of writing with a stylus pen into a digital image. Such technologies can rely on resistive, capacitive, optical, magnetostrictive, acoustic, mechanical, inertial, or electro-magnetic properties to name some. Complex signal processing software along with very fast processors can create remarkably detailed images with the input provided by a stylus pen. However, while stylus pens are highly functional in creating line art, there has been little advancement of recreating digital painting analogous to using paintbrushes. Partly, the slower advancement of digital brush painting may be due to the more complex movement of the brush bristles that have to be modeled. Each brush bristle may have a different touch angle and contact pressure. Even considering the complex signal processing and effects that can be created digitally, the stylus pen is unable to exactly recreate the effects of a paintbrush on a digital medium.